JPS62194686A - Optically coupled semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a high transmission efficiency and a high capability of removing the same phase without any alteration of conventional manufacturing technique by a construction wherein a lead frame whereon a light-receiving element is mounted is set at the electrically lowest potential in a circuit on the light-receiving element side, the shape of the lead frame is so changed as to interrupt a light-emitting element from the light-receiving element, and further the two elements are sealed in the same transparent resin. CONSTITUTION:A light-emitting element 1 is mounted on a terminal 7 and a light-receiving element 2 on a terminal 8. The two elements are covered with transparent resin 4 and further with white-opaque resin 5, so as to increase the rate of arrival of light at the light-receiving element. Furthermore the two elements are sealed up finally by light-intercepting resin 6. The end of the terminal 8 is so formed as to interrupt the light-emitting element from the light-receiving element. A light outputted from the light-emitting element passes with diffused reflection through an optical path formed of the resin and reaches the light-receiving element in a track shown by a dotted line in the figure.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optically coupled semiconductor device realized by combining a light emitting element and a light receiving element in a spatially separated state, and is particularly applicable to high speed data transmission systems. The present invention relates to an optically coupled semiconductor device with improved common-mode signal removal ability when

[Conventional technology]

Conventionally, as shown in FIG. 5, optically coupled semiconductor devices have mainly been in the form of a light emitting element 1 and a light receiving element 2 facing each other for the purpose of increasing transmission efficiency. In addition, 3 in the figure is the light receiving surface, 4
5 is a transparent resin, and 5 is a cloudy resin.

6 is a light-shielding resin, and 16.17 is a terminal.

In this example, the following measures are taken to improve the common mode removal ability of the optically coupled semiconductor device.

(1) Cover the vicinity of the light-receiving surface of the light-receiving element with a metal vapor-deposited wire having the lowest potential (generally GND potential) in the light-receiving element circuit.

(2) Cover the light receiving element 5 with a transparent conductive resin, and also ground the resin to the lowest potential.

By the above method, the Beret I itself has a shielding function, and the capacitance on the light emitting element side and the light receiving element side is substantially reduced, thereby increasing the in-phase signal removal ability.

(Problems to be solved and improved by invention) The conventional methods described above each have the following drawbacks.

(1) Since the shielding material 1'l is a metal vapor-deposited thin film, it virtually does not pass through the tip, so the light-receiving surface itself, which is sensitive to weight magnetic fluctuations in the circuit, cannot be covered, thus reducing the shielding effect. (2) Although it is a conductive resin, its specific resistance is several to +Ω
(It is 1 m, which is quite high compared to metal, and the shielding effect is also low. Also, in order to lower the specific resistance, a large amount of conductive additives are used, which reduces the light transmittance and reduces the transmission efficiency. Furthermore, it becomes difficult to mold the resin.

For the above reasons, it has been difficult to increase the common-mode signal removal ability without impairing the basic characteristics of the optically coupled semiconductor device.

The object of the present invention is to
The object of the present invention is to provide a complete and semiconductor device that can improve high transmission efficiency and common-mode signal removal ability.

(Means for Solving the Problems) The optically coupled semiconductor device of the present invention is realized by combining a light-emitting element that converts an electrical signal into an optical signal and a light-receiving element that converts the optical signal into an electrical signal. In a coupled semiconductor device, a lead frame on which a surface layer photodetector is mounted is set to a potential that is the electrically lowest potential in the circuit on the side of the photodetector, and the light emitting element is further deformed by deforming the lead frame. and the light-receiving element, and encapsulating both elements in the same transparent resin.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a longitudinal cross-sectional view of one embodiment of the present invention, FIG. 2 is a cross-sectional view at the element surface position of FIG. 1, and FIG. 3 is a longitudinal cross-sectional view showing the operating principle of the optically coupled semiconductor device of the present invention. It is a front view.

As shown in FIGS. 1 and 2, in this embodiment, the terminals 7 to 14 are formed on the same plane. A light emitting element 1 is mounted on the terminal 7, and a light receiving element 2 is mounted on the terminal 8. Both elements are covered with transparent resin 4. Furthermore, 1 of transparent resin 4 is replaced with cloudy resin 5.
By covering it with a light-shielding resin 9, the arrival rate of the light-receiving element \\ is increased.Finally, it is sealed with a light-shielding resin 6 for the purpose of preventing interference of external light.

Here, as seen in FIG. 1, the terminal 8 is shaped so that its end blocks the light emitting element and the light receiving element. If a sharp rising or falling voltage is applied between terminals 7 and 8 (i.e. between input and output), the lines of electromagnetic force existing between both terminals will go almost straight, as shown in the diagram explaining the operating principle in Figure 3. Therefore, the electromagnetic flux density distribution is as shown by the solid line in the figure.

However, on the other hand, the light output from the light emitting element passes through the optical path provided by the resin mentioned above while being diffusely reflected.
It reaches the light receiving element by drawing a trajectory as shown by the dotted line in the figure.

Since the terminal 8 is grounded to the lowest potential in the light receiving side circuit diagram, it has the effect of shielding the light receiving element against potential fluctuations on the input side.

Although the transmission efficiency is inferior to that of the conventional opposing type, it is easy to prepare a light emitting element that compensates for this drawback because relatively low-priced high-brightness light emitting elements have recently appeared on the market.

FIG. 4 is a longitudinal sectional view of another embodiment of the invention.

The operating principle of this embodiment is no different from that described above, and it is considered that this embodiment has a better shielding effect.

〔Effect of the invention〕

As explained above, the present invention, in a coplanar optically coupled semiconductor device, sets the lead frame on which the light receiving element is mounted to the electrically lowest potential in the light receiving element side circuit, and By deforming the frame, the light-emitting element and the light-receiving element are blocked, and both elements are encapsulated in the same transparent resin, achieving both high transmission efficiency and high common-mode rejection capability without any changes to conventional manufacturing technology. An optically coupled semiconductor device having both of the following can be obtained.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of an embodiment of the present invention, FIG. 2 is a cross-sectional view at the element surface position of the embodiment of the present invention shown in FIG. 1, and FIG. 3 is an optically coupled semiconductor device of the present invention. FIG. 4 is a vertical cross-sectional view of another embodiment of the present invention, and FIG. 5 is a vertical cross-sectional view of an example of an optically coupled semiconductor device of the Congo Sung Dynasty. DESCRIPTION OF SYMBOLS 1... Light-emitting element, 2... Light-receiving element, 3... Light-receiving surface, 4... Transparent (A fat, 5... Cloudy resin, 6... Light-shielding resin, 7-17...・Terminal. Core L Concave Figure 3

Claims (1)

[Claims] In an optically coupled semiconductor realized by combining a light-emitting element that converts an electrical signal into an optical signal and a light-receiving element that converts an optical signal into an electrical signal, a lead frame on which the light-receiving element is mounted is connected to the light-receiving element. The electrical potential in the side circuit is set to the lowest electrical potential, and the lead frame is further deformed to block the space between the light emitting element and the light receiving element, and both elements are encapsulated in the same transparent resin. Features of optically coupled semiconductor devices.